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1.
A theoretical analysis on the two extreme cases of yarn bending rigidity as well as the relationship between them is proposed. The significant influence of fiber-to-fiber interaction on yarn bending rigidity is revealed. Experimental observation on the relationship between fabric/yarn bending property and fiber fineness, yam structure, fabric structure is given as well. Three problems are discussed and the following conclusion is thus obtained. There exists, similar to a rigid engineering rod, a linear relationship between yarn bending rigidity and the square of yarn fineness (expressed as yarn count in tex), but the increasing speed is much lower. Yarn bending rigidity in the fabric also to a great extent depends on the fabric density and yam twist factor, and so on. Fabric's bending hysteresis primarily depends on its bending rigidity.  相似文献   

2.
To investigate the spring-back behavior of dual-phase (DP) steel, V-shape spring-back experiments with different bending angles, relative bending radii and blank holding forces were carried out in this paper. It is concluded that with the increase of V-shape angle or blank holding force, the spring-back of DP steel sheets decreases; while raising fiIlet radius of punch, which has the most apparent effects on spring-back, advances spring-back angle. Among DP590, DP780 and DP980, higher strength yields more notable spring-back due to larger elastic deformation. The difference of spring-back among these materials is relevant with the microstructure and mechanical properties. The total elastic deformation approximately equals the ratio of the strength corresponding to the applied load to the modulus of elasticity.  相似文献   

3.
Experimental results of 29 axially loaded fiber-reinforced polymer sheet (FS) confined concrete columns and two reference plain concrete columns are introduced. Twenty four column specimens were confined with carbon fiber sheet (CFS) and five column specimens were hybrid confined with both CFS and glass fiber sheet (GFS). The influence of aspect ratio, FS material, initial axial force ratio, and FS confinement degree on the strength and deformation of columns were studied. Based on the experimental results, the equations of complete stress-strain curve of CFS confined concrete are proposed. These equations are suitable for the nonlinear analysis of square and rectangular section columns. Suggestions of applying FS to confine concrete columns are presented.  相似文献   

4.
A new method is presented to prevent the wool fabric from shrinking effectively by using cocoon stripping blended with wool fiber. The sericin of cocoon stripping is used as resin to bond the wool fiber together after heat setting. The factors affecting the effect of shrinkproofing is heat setting temperature, wool/cocoon stripping blending ratio, cover factor, regain of fabric. Temperature of heat setting and the blending ratio of cocoon stripping are the two key factors. This method does not pollute the environment, and almost has no damage on wool fiber.  相似文献   

5.
In this paper,workability,strength and durability of coal gangue coarse aggregate concrete with different steel fiber content levels have been studied.The results indicate that the concrete compressive strength,flexural strength and tensile splitting strength at the age of 28 days increase with the steel fiber content increasing,while cost and impermeability reduce with steel fiber content increasing.Based on the data of the workability of fresh concrete,mechanical properties and durability of hardened concrete,the concrete cost index system are established to evaluate and optimize the steel fiber content in coal gangue concrete by Efficacy Coefficient Method.The optimization result reveals that the maximum value of the system efficacy coefficient is up to0.87,the coal gangue concrete with steel fiber 1.5%(V︰V)performs better.  相似文献   

6.
High durability and high tensile strength makes ultra-high performance concrete( UHPC) an ideal material for bridges,while its early shrinkage in the construction of cast-in-situ mass concrete leads structure crack-easily,which restricts the application of UHPC in deck system. Whether reasonable amount of coarse aggregate can influence the strength of UHPC and improve the shrinkage performance or reduce the cost is still in doubt. Besides,in order to improve its constructability and workability, whether autoclaved curing system of UHPC can be changed remains to be further researched. In response to these circumstances, a systematic experimental study on the strength of UHPC mixed with coarse aggregate in different ratios has been presented in this paper. The three curing systems,namely standard curing,180-200 ℃/1. 1 MPa autoclaved curing,and hot water curing were tested to reveal the relationship between UHPC's properties and curing systems,and the UHPC ' s microstructure was also preliminarily studied by scanning electron microscope( SEM). The experimental research can draw the following conclusions. Under the condition of the same mix ratio, autoclaved curing guarantees the highest compressive strength,followed by hot water curing and standard curing. The compressive strength of concrete increases with the temperature in the range of 25 to 90 ℃ hot water curing,and high temperature in precuring period can speed up the strength development of UHPC,but the sequence of precuring period does not obviously affect the results. In 90 ℃ hot water and autoclaved curing,the strength is over 150 MPa,and it has little relation with gravel ratio. While the value increases first and then decreases in a lower temperature curing with the increasing of gravel amount,even only about 80 MPa at room temperature. The strength increases moderately along with the increase of the curing age by standard curing,especially in the initial stage.  相似文献   

7.
Taizhou Yangtze River Bridge is a suspension bridge with three pylons and two 1080m main spans. The middle pylon is a steel frame with longitudinal herringbone shape and lateral gate shape. The connection between steel pylon and concrete pile cap is a key part to transfer the huge inner force from the pylon to the foundation. Its construction quality is a critical factor to the overall structural loading of the whole bridge, therefore the contact ratio between the bearing steel plate of pylon and concrete pile cap is required to be over 75%. The inclined joint surface in two directions, longitudinally at 39/1920 and laterally at 1/4, posted a challenge to the construction works. Technological tests were carried out to find an optimal construction method by comparison, and finally the Post-Injection method was selected as it can meet the requirement of concrete strength and contact ratio at the connection. The successfully application of the Post-Injection method at Taizhou Yangtze River Bridge has provided an example and reference for similar projects in the future.  相似文献   

8.
Interface morphology has important influence on the bond quality of titanium clad steel plates. The mechanical properties of titanium clad steel plates with wavy and straight interfaces were investigated by tensile-shear tests and bending tests. The interface morphology of the plates was examined by optical microscopy (OM) and scanning electron microscopy (SEM). The experimental results show that the shear strength of a wavy interface is higher than that of a straight interface. A wavy interface is the guarantee for obtaining high shear strength to provide a greater shear resistance. During the macrobending process, cracks appear in the swirl of the wave tip and ferrotitanium intermetallics. For in-situ observing the bending process by SEM, the wave tip of a wavy interface and the massive ferrotitanium intermetallics of a straight interface are places where cracks initiate and propagate. The results are the same as those observed in the macrobending process. Because of high hardness, the wave tip and the massive ferrotitanium intermetallics are hard in terms of compatible deformation.  相似文献   

9.
It is introduced in this paper that a high strength and high toughness X70 pipeline steel with an ultra-low acicular ferrite microstructure has been researched and developed at Baosteel according to the requirements of the West-East Gas Pipeline(WEGTP) project. The developed steel has higher strength, higher toughness, lower ductile-brittle transition temperature and higher dynamic tear-resistance than the conventional X70 with ferrite and pearlite microstructure. The excellent properties of the steel are benefited from ultralow carbon acicular ferrite consisting of interaction of very fine precipitated particles and high-density dislocation. And the steel has been applied on the WEGTP in China.  相似文献   

10.
The bonding of solid steel to liquid aluminum was conducted using rapid solidification. The influence of diffusion time on interfacial shear strength was studied. The results show that when the temperature of aluminum liquid is 700℃ and the preheat temperature of steel plate is 250℃, the relationship between diffusion time (t) and interfacial shear strength (( ) is ( =15.1+8.14t(037t2 +0.005t3, and the maximum interfacial shear strength is 71.1 MPa.  相似文献   

11.
Nanometer ferromagnetic metal-semiconductor matrix Fe−In2O3 granular films are fabricated by the radio frequency sputtering. Magnetic properties and the giant magnetoresistance (GMR) effect of Fex(In2O3)1−x granular film samples are studied. The result shows that the magnetoresistance (MR) ratio Δρ/ρ 0 value of the granular film samples with Fe volume fraction x=35% is 4.5% at room temperature. The temperature dependence (T=1.5–300 K) of the MR ratio Δρ/ρ 0 value of Fe0.35(In2O3)0.65 granular films shows that Δρ/ρ 0 value below 10 K increases rapidly with the decrease of the temperature, and when T=2 K, Δρ/ρ 0 value is 85%. Through the study of the dependence of low field susceptibility on temperature and the hysteresis loops at different temperatures, it has been found that, when the temperature decreases to a critical point T p=10 K, the change of the structure in Fe0.35)In2O3)0.65 granular films results in the transformation of state from ferromagnetic to spin-glass-like. The remarkable increase of the MR ratio Δρ/ρ 0 value of Fe0.35(In2O3)0.65 granular films below 10 K seems to arise from the peculiar conducting mechanism of the granular film samples in the spin-glass-like state.  相似文献   

12.
0 IntroductionLetDdenotetheopenunitdiskinthecomplexplaneC , DitsboundaryanddAtheLebesguemeasureonD ,normal izedsothatA(D) =1.ForaBanachspace (X ,‖·‖X) ,wewriteH(D ,X)fortheclassofallX valuedanalyticfunctionsonD .Let1≤ p<∞ ,theX valuedBergmanspaceBp(X)istheclassofallf∈H(D ,X) forwhich‖f‖Bp(X) =∫D‖f(z)‖pXdA(z) 1 /p <∞ (1)IfX =C,thenwewriteBp =Bp(C) fortheclassicalBergmanspaces.Letφ∶D→Dbeananalyticself mapofD .Thenthee quation Cφf=f φdefinesacompositionoperator…  相似文献   

13.
0Introduction Near infrared(NIR)techniquesarebasedonsensitive,quantitativemeasurementsoffunctionalcontrastbe tweenhealthyanddiseasedtissue.Recently,researchersshowgreatinterestinmeasuringfunctionalpropertiesofbreasttis suesuchashemoglobinconcentrationoroxygensaturationbyNIRspectroscopyandNIRimaging[1,2].NIRlightcanpene trateseveralcentimetersintotissuebeforeitisattenuatedbe lowdetection.ThemainintrinsicmechanismsofNIRlightat tenuationintissuearethescatteringduetoindexofrefractionvariatio…  相似文献   

14.
We consider the Poisson integral u = P*μ on the half-space R+^N+1 ( N 〉 1 ) (or on the unit ball of the complex plane) of some singular measureμ. If μ is an s-measure (0 〈 s 〈 N), then some sharp estimates of the integration of the harmonic function u near the boundary are given. In particular, we show that fpr p〉1,∫R^Nu^p(x,y)dx- y^-τ (y〉0,τ =(N-s)(p-1) ) (Given for p〉1, RN f 〉 0 and g 〉 0, " f-g " will mean that there exist constants C1 and C2, such that C1f ≤ g ≤ CEf ).  相似文献   

15.
In(Phys Lett A,2002,297:4-8) an entanglement criterion for finite-dimensional bipartite systems is proposed:If ρ AB is a separable state,then Tr(ρA2) Tr(ρ2) and Tr(ρB2) Tr(ρ2).In the present paper this criterion is extended to infinite-dimensional bipartite and multipartite systems.The reduction criterion presented in(Phys Rev A,1999,59:4206-4216) is also generalized to infinitedimensional case.Then it is shown that the former criterion is weaker than the later one.  相似文献   

16.
This study is aimed to investigate and analyze the vegetation landscape around Rivers of Hou-lung, Fa-tz, Da-li, Ching-shuei and Gau- ping, and to select the suitable plant species that could be applied for the area of riverbank ecological engineering in Taiwan. Studying the vegetation established the key point and procedure of ecological engineering in the riverside and revetment, to compile and edit the dominant plants' types, life form, propagating method, root systems' characteristics and functions for soil conservation. This research choses three dominant plants for roots strength test. The fitting models of plants pulling resistance(Rp, kg) between plant height (H, cm), diameter near ground (Dn, mm), diameter above ground 100 mm (Da, mm), The research finished the relative abundant, types and cluster analysis of riverbank dominant plants that generalize vegetative distribution and ecological restoration for different river types to apply and manage in Taiwan.  相似文献   

17.
层布式钢纤维混凝土的抗折强度的影响因素分析   总被引:2,自引:2,他引:0  
试验研究了不同长径比和掺配率对层布式钢纤维混凝土的抗折强度的影响规律,确定最佳长径比和掺配率;结合本课题组以往的试验和国内有代表性试验,分析影响层布式钢纤维混凝土抗折强度的主要因素:钢纤维长径比、掺配率、减水剂、纤维型状.  相似文献   

18.
This paper deals with the problem of the type △nf f^p=0 in quaternionie Heisenberg group, where △n is the quaternionic Heisenberg Laplacian. It is proved that, un der suitable conditions on p and f. the only solution of △nf f^P=0 is f=0.  相似文献   

19.
Three suborder soils in southwest China were adopted, namely Ustic Vertisol, Stagnic Anthrosol and Ustic Ferrosol, so as to carry out the basic physical and chemical analysis respectively, to design a dynamic measuring method for water stability of soil structure and conduct the comparative study on the quality of the soil structure. The results indicated that (1) The water stability dynamic characteristic of the soil structure could well reflect the maintaining capability of the soil structure as time goes on. (2) The quality of several soil structures in southwest China was sequenced as follows: Stagnic Anthrosols 〉 Ustic Vertisols 〉 Ustic Ferrosols. (3) The water stability of soil structure is very positively correlated with the capillary porosity and the clay particle (D 〈 0.002 mm) content (Co), but is very negatively correlated with the silt (D is 0.05-0.002 ram) content (Csc), and (4) The dynamic functional equation of the water stability of soil structure in southwest China was established, so that the water stability characteristics of various soil structures could be quantitatively expressed and the quality of different soil structures can be quantitatively compared from each other.  相似文献   

20.
0Introduction Changesinsoilstructureoftenaccompanychangesinmanagementpracticesandmayaffecttheeffectivenessofthesepractices.Parametersareneededto quantifythesechanges.Sizedistributionsofsoilparticleandmicroaggregatehavebeenfoundtobeagood indicatorofchanges…  相似文献   

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